I agree with Chris's comments about the ego of who to protect and not to protect. At some level you simply need to remove yourself from the ethics...to a degree...and realize you are hired or commissioned to protect and to prevent violence from occurring.

You are not the politician nor do you participate furthering their agenda...you are simply there to stop harm.

That said, of course, I personally would try and choose my clients wisely and there are some li its to who I would choose to not serve. However, in the grater scheme of things...philosophically, stopping harm or violence is the business you are in and that morality I believe comes before the other stuff.

Forget ego and politics. And never forget ethics, not to any degree. Unless propping up and protecting assholes is your business. I've never been in the military and I say that proudly. Why? Because I don't believe in doing violence to people on order of others.